A laser model for narrow-striped DH lasers, in which there is good carrier confinement as well as good optical confinement, is proposed and analysed. Such conditions are encountered in the buried-heterostructure laser, the stripe buried-heterostructure laser, and the buried-optical-waveguide-structure laser. It is found that the model is stable, showing no self-sustained oscillations, when the value of the factorhis greater than 350. The factorh= (2πLe/W)2, whereLeis the effective diffusion length of carriers in the active layer andWis the stripe width. A device is proposed, which will generate high-speed optical pulses in a predictable and reproducible manner.